Cooling arrangement for electrical apparatus



COOLING ARRANGEMENT FOR ELECTRICAL APPARATUS Filed July 15, 1929 3 Sheets-Sheet 1 Figi.

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COOLING ARRNGEMENT FOR ELECTRICAL APPARATUS Filed July l5, 1929 3 Sheets-Sheet 5 FiglL.

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Patented Apr. 7, 1931 JOHN LINDLEY THOMPSON, OF HAYES, ENGLAND COOLING, ARRANGEMENT FOR ELECTRICAL APPARATUS Application led July 15, 1929, Serial No. 378,459, and in Great Britain August 11, 1928.

This invention has reference to improvements in means for dissipating the heat generated in electrical apparatus of different kinds immersed in liquid within a casing,

and particularly for dissipating. the heat generated in an electric transformer contained Within an oil filled tank.

For dissipating the heat generated in electrical apparatus immersed in liquid (hereinafter referred to as oil), contained within a casing or tank (hereinafter referred to as a tank), the top and bottom of the tank has usually been connected to a number of external vertically arranged air cooled tubular radiators, of various constructions, through which oil heated within the tank by the electrical apparatus, when the same is in use, is caused to flow by natural circulation, due to dierence in the temperature of the oil at the top and bottom of the tank. Sometimes the tubular radiators have been traversed by tubes through which a cooling fluid, for instance water or air, is caused to flow, toincrease the dissipation of heat from the oil, and in other cases the oil has been withdrawn from the upper part of the tank v through a pipe by a circulating pump and passed through an external water cooled tubular cooling device from which it is returned through another pipe to the bottom of the tank.

Now the Vpresent invention has refer-eme to a cooling arrangement suitable for use with oil cooled electrical apparatus, for instance an electrical transformer arranged within a tank filled with oil, and comprising external air or water cooled radiators connected to the top and bottom of the tank,

. transformer.

For this purpose, the lower ends of the external radiators of the oil tank are connected by kpiping to the inlet of an oil circulating pump and the outlet of such pump is connected to the bottom of the tank so that the oil can be forced to flow rapidly through the radiators and more slowly through the tank and in contact with the transformer or other electrical apparatus (hereinafter referred to as the transformer) therein so as to maintain the oil at a nearly uniform temperature throughout the circulating system, as when the transformer is working at or near full load, and each radiator is also connected to the lower end of the tank through a valve controlled pipe that is closed when the pump is in operation and is opened when the transformer is working at a low or lower load, so that the natural circulation of the oil through the radiators and tank can then take place and the pump be put out of operation so as to avoid the cost of running it at this time. The valves controlling the direct communication between the lower ends of the radiators and the bottom of the tank may advantageously be non-return valves adapted to close automatically when the pump is put in operation and to open inwardly in an automatic manner when the pump is stopped. In the accompanying illustrative drawings, Fig. l shows in elevation and Fig. 2 in plan one construction of oil cooling means according to the invention applied to a transformer tank, provided with air cooled radiators. Fig. 3 is ay detail View. Figs. 4 and 5 are similar views to Figs. l and 2 showing a modified arrangement. F (i and 7 show diagrammatically other modified arrangements. Fig. 8 shows the invention applied to a transformer provided with water cooled radiators.

Referring to the example shown in Figs. l and 2 of the drawings, the external vertical air cooled radiators l arranged around the transformer tank 2, are connected at their upper ends or headers la by valve controlled junction pipes 3 to the upper part of the tank so that warm oil can enter them from the tank, and at their lower ends are connected by vertical pipes 4 to a lower horizontal pipe 5, that extends around the tank 2, is of larger cross sectional area than each of the vertical pipes 4 and is connected at different points in its length to suction pipes 6 connected to the flow of oilthrough all the radiators, the delivery side of the pumps being connected by other pipes 8 to different points of the lower end of the tank 2. The lower ends, or headers 1b of the radiators 1 are also connected direct to the bottom of the tank through horizontal p-ipes 9 provided with controlling valves 10 and are preferably inwardly opening sensitive non-return valves for the reason hereinbefore mentioned. A valve of this kind is shownin Fig. 3 in section and to a. larger scale than Figs. 1 andl 2. Itcomprises a flap valve 10 mounted in a casing 10a to open inwardly, so that when the pumps 7 are working it will be closed against its 'seat 10b by the'sucking action of the pump, but will be opened automatically by the pressure ofthe oil descendin g in the radiator, caused by natural circulation, when the pumps are stopped. A flap 11 may, as shown, be suspended in the oil passage 10C by av` flexible diaphragm 112Lv and be provided with an external pointer 11b arranged to work over an indicator face 11c whereby it can-be ascertained whether the valve 10 is open or closed. The valve 10,7in the example shown, isV carried by a link 10d pivoted at 1()e and provided with an arm 10f' whereby the valve can be held closed by a locking'screw 10g when this may befdesired, as for instance, when it is desired to disconnect they radiator from the tank. Hand controlled valves could of course be used instead of the automatic valves but obviously not so advantageously.

Instead of connecting the lower end of each radiator 1 to the bottom of the tankby a valve ycontrolled pipev 9, as hereinbefore described,

the horizontal pipe 5 to which the radiators are connected, may, as shown in Figs. 4 and 5, be connectedV at a number of points in its length tol the lower Vportion of the tank through pipes 9a provided with controlling Vva ves 10 for the purpose set forth. In this example, the valves 10 are shown as hand operated sluice valves. ln this example also, the header 1LL at the upper end of each radiator 1 is connectedlaterally to the upper end of the tank Q. by a Valve controlled T-shaped Vpipe 3 to which another radiator can be connected, Vas shown at 1c so that one pipe 3* can becommon to two radiators. Also, the headers 1" at the lower end of the radiators 1 are connected laterally to valve controlled T-shaped pipes 9a, the several pipes 9a being Vconnected through the said lower headers 1b to the suction pipe c connected to the pumps 7.

YEach pumpy 7 may, as shown in Figs. 1 and 2, be arranged to be driven by a pulley 7L and belt from an electric or other motor, not

shown, or, V as shown in Figs. 4 and 5, each pump may bearranged to'be driven direct by'an electric motor 12.

Y 'If desired or required, a tubular' water VVVcooled device 13 may, as indicated iii Fig. 6, be

connected in a shunt conduit to an oil delivery pipe 8 of each circulating pump 7 so that by Closing a valve 14 in the said pipe between its points of connection to the tubular water cooled device 13, the oil, after leaving the pump, can be caused to flow through suoli cooling device on its way to thejbottoni of the tank. Y I

Fig. 7 shows, diagrammatically, how the lower ends of radiators 1 connected by valve controlled pipes 9 can Vbe connected by the suction pipes 6 toa single pump 7 connected by delivery pipes 8 to the bottom of the tank 2.

The radiators may, as hereinbefore stated, be water cooled radiators. One such radiator is shown at 15 in Fig. 8, 15L eing the water inlet and 15b the water outlet. The lower end portions of such radiators are connected laterally through pipes to the oil circulating pump or pumps as in the other arrangements hereinbefore described.

The cooling arrangements hereinbefore de-v scribed are specially suitable for use with an oil cooled transformer having a self cooled rating and a forced cooled rating.

' By the use of cooling arrangements such as hereinbefore described, a more efficient use of the radiating surfaces available can be obtained, and the flow of oil in the cooled radiator units can be more equally distributed than is usual with forced cooled units, thus ensur-V ing more uniform temperature throughout the transformer orv other electrical apparatus soA enclosed in the tank. Consequently, by using I such cooling arrangements with standard lnaturally cooled transformers or units, large overload capacities are available. Furthermore, the cooling effect can lie-made automatic, thus eliminating the'human element.

Whatl claim is:- Y' A 1. A cooling arrangement suitable for use with liquid cooled electrical apparatus,com

prising, in combination'with tank for the electrical apparatus, external radiators each connected at its upper end tothe lupper part of said tank, an oil circulating pump to which ico llO

the lower ends of said radiators are connected Y.

and which is in communication at its delivery side with said tank, and a valve controlled connection between the lower end of each radiator and the lower end of said tank, said connections being capable of being closed l when said pump is in operation and of beiing opened when said electrical apparatus is working at a low'loadand thepump is out of operation. Y

.2. A cooling arrangement suitable for use with liqui-d cooled electrical apparatusv coniprising, in combination with a tank for the electrical apparatus, external radiators each connected at its lupper end to the upper part 0f said tank, an oil circulating pump to which the lower ends ofV said radiators are connected and which is in communication'atits` delivery side with said'tank, and a valveconypipe of said circulating trolled connection between the lower end of each radiator and the lower end of said tank, the valve controlling each of said connections being a non-return valve adapted to close automatically when said pump is put in operation and to open inwardly in an automatic manner when said pump is stopped.

3. A cooling arrangement according to claim 1, having a secondary cooling device connected in shunt to the liquid delivery pump and valve means whereby said secondary cooling device can be put in and out of use at will, for the purpose described.

4. A cooling arrangement suitable for use with liquid cooled electrical apparatus, comprising, in combination with a tank for the electrical apparatus, external radiators each connected at its upper end to the upper part of said tank, a pipe extending around said tank, tubular connections between the lower ends of said radiators and said pipe, an oil circulating pump the sucti-on of which is in communication with said pipe and the delivery side of which is in communication with the lower end of said tank, tubular connections between the lower ends of said radiators and the lower end of said tank and controlling valves in said last mentioned tubular connections.

5. A cooling arrangement suitable for use with liquid cooled electrical apparatus, comprising, in combination with a tank for the electrical apparatus, external radiators each connected at its upper end to the upper part of said tank, a pipe extending around said tank, tubular connections between the lower ends of said radiators and said pipe, an oil circulating pump the suction side of which is in communication with said pipe and the delivery side of which is in communication with the lower end of said tank, tubular con nections between the lower ends of Asaid radiators and the lower end of said tank, and inwardly opening non-return valves in said last mentioned tubular connections.

6. A cooling arrangement for cooling liquid in a tank, comprising, in combination with the tank, external radiators connected at their upper and lower ends to the upper and lower end portions of the tank, valves for controlling the communication between the lower ends of the radiators and the tank, a liquid circulating pipe common to said radiators, tubular connections between the lower ends of said radiators and circulating pipe, and a plurality of pumps connected on their suction side to said pipe and on their delivery side to the lower tank.

7. A cooling arrangement for cooling liquid in a tank, comprising, in combination with the tank, external radiators connected at their upper and lower ends to the upper and lower end portions of the tank, autoportion of said matic inwardly opening non-return valves between the lower ends of said radiators and tank, a liquid circulating pipe common to said radiators, tubular connections between the lower ends of said radiators and circulating pipe, and a plurality of pumps connected on their suction side to said pipe and on their delivery side to the lower portion of said tank.

S. A cooling arrangement for cooling liquid in a tank, comprising, in combination with the tank, external radiators connected at their upper and lower ends to the upper and lower end portions of a tank, automatic inwardly opening non-return valves between the lower ends of said radiators and tank, means adapted automatically to indicate the openl or closed position of said non-return valves, a liquid circulating pipe common to said radiators, tubular connections between the lower ends of said radiators and circulating pipe, and a plurality of pumps connected on their suction side to said pipe and on their deliverj7 side to the lower portion of said tank.

Signed at London, England, this fifth day of July, 1929.

JOHN LINDLEY THOMPSON. 

